A growing number of former residents have cancer, and sources involved in cleaning up the former military base say the Navy has deceived the people who live there now.

Ashley BatesThroughout the island, the Navy has found small disks, some of which contain very high levels of radium-226, a dangerous toxin.

Kim KellnerKim Kellner survived breast cancer and her close friend, Sam Tyo, died of stomach cancer in 2005.

Ashley BatesOfficials allowed people to move to Treasure Island in the late 1990s despite the health risks.

Ashley BatesIn 2008, workers in Hazmat suits dug up the area behind Margaret Billsborough's then home.

Ashley BatesA contaminated work site is across the street from the island's only child development center.

Ashley BatesShaw Environmental left the gate open to an area where dangerous radioactive materials are stored.

Ashley BatesKathryn Lundgren saved floodwater that kids played in after it had flowed from radioactive sites.

This article won first place for news story (non-daily newspapers category) at the San Francisco Peninsula Press Club’s Greater Bay Area Journalism Awards in 2013.

Margaret Billsborough has survived unspeakable traumas: childhood abuse, wrenching poverty, homelessness, and crack-cocaine addiction. So when she, and many other vulnerable people like her, were given the opportunity to move into an apartment on San Francisco's Treasure Island, it seemed like a dream come true. Here, she thought, was a quiet, idyllic refuge where she could begin to heal.

What she didn't know at the time was that the former Naval base was strewn with radioactive waste. She did not know that many past residents now have cancer. She did not know that cleanup workers, lawyers, activists, and health officials have been trying for years to sound the alarm.

But she did sense that something was not quite right. She was told not to plant vegetables in her yard. The lease she signed warned, "This apartment community contains ... substances known to the State of California to cause cancer and/or birth defects." When she walks around the island, she sees many fenced-off sites with signs that state, "Warning: Radiologically Controlled Area." One of these radioactive sites is adjacent to the Boys & Girls Club, where her kids often played.

From Billsborough's perspective, the Navy, which oversees the cleanup, doesn't really care about her family, despite the cheery newsletters it sends out, reassuring residents about the cleanup process. In 2008, Billsborough and her two youngest daughters — ages seven and nine at the time — woke up to find workers in blue Hazmat suits and masks digging up a common area right behind her backyard on 1244G North Point Drive. No one had told her that these workers were coming. Her window was wide open. Alarmed, she called her caseworker and property manager. While the cleanup workers were still digging, an official from the Navy showed up. He apologized for not telling her to shut her window, called off the dig, and told the workers to leave.

"It was never reported anywhere," Billsborough said. "Nothing was ever done. Nobody ever came and said, 'Do you want to get checked out from the doctor?' Nothing. They were just like, 'These people are in low-income housing. They really don't know who to talk to and what to do about it anyway.' And I feel that that's how they view us out here."

After my conversation with Billsborough at her home in early August, The Bay Citizen published two news reports, on August 17 and 28, that featured excerpts from emails and memos between the Navy and government agencies, some of which suggest that the danger of radioactive waste on Treasure Island has been poorly assessed and underreported. The emails also show that the Navy has attempted to stymie its strongest critic, the California Department of Public Health. Many Treasure Island residents, including Billsborough, are now terrified about their children's long-term health. They are beginning to band together and confront the authorities.

Created from a landfill in 1937 for the 1939 and 1940 Golden Gate International Exposition, Treasure Island opened in 1942 as a naval base during a period when the US government was testing nuclear bombs in the Pacific. The base was used, in part, to repair ships that the Navy recently acknowledged might have been exposed to nuclear waste, and also served as a training center for nuclear decontamination, which involved the use of radium-226 and other radioactive materials.

Radium-226 is one of the more dangerous toxins in the world. While some radioisotopes have short half-lives — i.e., the time it takes for the toxicity of a substance to be reduced by half — radium-226 has a half-life of 1,600 years. Radium-226 is therefore almost as toxic today as it was sixty years ago. The greatest risk is ingestion. Depending on the form by which it is ingested, it may never leave a person's body — the body treats radium-226 like calcium and consequently it moves into the bones. This means that when you ingest radium-226, you likely ingest it for life. The heightened risk of cancer and other illnesses may stay with you forever.

The dangers of exposure to radioactive materials were less understood in the 1940s, 50s, and 60s, and contamination cleanup was far less thorough than it is today. The island may have been polluted during the cleanup of a nuclear training ship called the Pandemonium or by mistakes made during nuclear decontamination trainings conducted on the island. In 1950, after 40 milligrams of radium sulfate powder was spilled in a Navy lab, students and instructors inadvertently tracked the powder to other areas. Additionally, the Navy has found octagonal, 1-inch- and 1.5-inch-diameter metal disks throughout the island from an unknown source; some of these disks contain very high levels of radium-226.

According to two confidential sources who have been involved in aspects of the Treasure Island cleanup, the Navy has deceived residents in the past about the safety of the island and continues to deceive them now. Over the past five years, at least three shipments of extremely dangerous radioactive contamination — most of it from these metal disks — have been moved from Treasure Island to secure locations. One of these shipments left Treasure Island in 2007, another in 2009, and the third likely left in 2011. The level of radioactive contamination in these shipments was considered high. "If a person spent a few hours in close proximity to the material inside one of these shipments," one source said, "he or she could receive enough exposure to be dead within a month."